From there, he moved to North Carolina State. He played there in 1987 and 1988, when he was drafted. He made second-team All-ACC his first year, and first-team All-ACC his second.

With
the Expos, Kosco started at short-season Jamestown. He hit .284 in 63
games. He played 1989 between single-A Rockford and West Palm Beach, hitting .251 between them.

Kosco
made AA Jacksonville in 1990, but his season was limited to just 33
games. He returned to AA in both 1991 and 1992, hitting .241 and .229.
He hit 10 home runs in 1991, his 10th tying an August game.

Kosco moved to the Marlins system and high-A High Desert for 1993. He hit .307 in the lower league, with a career-high 27 home runs.